1. Field of the Invention
The present invention relates to a chemical liquid control valve for controlling supply of a chemical liquid.
2. Description of Related Art
In a CMP (Chemical Mechanical Polishing) process for semiconductor manufacture, wafers are polished by use of a chemical liquid (slurry) containing abrasive particles. Specifically, the wafers are rotated and polished with slurry supplied at a constant amount to the wafers under rotation. One of control valves for controlling the supply of slurry is e.g. a control valve disclosed in Jpn. unexamined patent publication No. 2002-310316.
A schematic configuration of this control valve is shown in FIG. 19. A control valve 120 includes an actuator 103 having a cover 101 and a cylinder tube 102, and a body 121 to which the actuator 103 is fixed. The body 121 is formed with a first hole 109 and a second hole 110, concentrically formed, which serve as an inlet port and an outlet port for fluid respectively, and further a flow passage 111 communicated with the first hole 109, as shown in FIG. 19. Provided on the end of a protruding part 112 centrally forming the flow passage 111 is a valve seat 113 having a valve port 113a communicated with the flow passage 111. A communication passage 122 is spirally formed around the protruding part 112 to allow communication between the valve port 113a and the second hole 110.
With the above structure, the control valve 120 can reduce the occurrence of an accumulation area near the inner wall of the communication passage 122 and also a turbulence area near the valve seat 113.